1. string转const char*

 string s = "abc";

 const char* c_s = s.c_str();

2. const char*转string

 直接赋值即可

 const char* c_s = "abc";

 string s(c_s);

3. string转char*

 string s = "abc";

 char* c;

 const int len = s.length();

 c = new char[len+1];

 strcpy(c,s.c_str());

4. char*转string

 char* c = "abc";

 string s(c);

5. const char*转char*

 const char* cpc = "abc";

 char* pc = new char[100];//足够长

 strcpy(pc,cpc);

6. char*转const char*

 直接赋值即可

 char* pc = "abc";

 const char* cpc = pc;